Thursday, April 9, 2009AFP

LONDON -- Police came under mounting pressure Wednesday after a video emerged showing a riot officer push a man violently to the ground, shortly before he died during last week's G-20 protests in London.

A police watchdog body is already investigating the death of Ian Tomlinson, 47, who suffered a heart attack while walking home from work during the protests last Wednesday, on the eve of the G-20 summit.

But the amateur video, obtained by the Guardian newspaper, triggered more questions from the family, and a call from opposition politicians for a criminal investigation.

“This video clearly shows an unprovoked attack by a police officer on a passer-by. It is sickening,” said David Howarth, justice spokesman for the opposition Liberal Democrats.

“There must be a full-scale criminal investigation. The officer concerned and the other officers shown in the video must immediately come forward.”

The Independent Police Complaints Commission, which probes allegations involving officers, said it would study the video footage as part of its investigation into the incident.

“We will be assessing this along with the other statements and photographs that have already been submitted,” said an IPCC spokeswoman.

A Scotland Yard spokesman declined to comment on the video, saying: “It would not be appropriate to comment while an IPCC investigation is ongoing.”

The video shows Tomlinson, who was walking home from his job at a newsagent, walking with his hands in his pockets in front of a line of officers, one of whom shoves him and causes him to fall on the ground.

The Guardian said a police officer also appeared to strike Tomlinson with a baton, hitting him from behind on his upper thigh, although this was not clear from the published footage.

Police said at the time that they had been alerted by a passer-by that Tomlinson had collapsed and was not breathing, and claimed protesters threw bottles and other debris at them as they tried to revive him.

Tomlinson was later pronounced dead in hospital. His family has appealed for anyone with any information about how he died to come forward.

The video was shot by a fund manager from New York shortly before Tomlinson died, the Guardian said.

Tomlinson's son Paul King, 26, said the video raised many questions about his father's death. “Whether that was a cause to his death we are not to know,” he said, cited by the Guardian.

“We want answers: why? Ian clearly had his arms in his pockets and back towards the police. There is no need for them to step in towards him. It clearly shows that Ian did have an altercation.

“Now we can say, yes he did. Up until now it has been 'if'. But now we've seen it, we want answers.”